Food to Avoid: Packaged cheese slices

"They're often processed and can taste like wax—yuck!" says Patricia Bannan, R.D., author of Eat Right When Time Is Tight. "I prefer to have full-fat cheeses; they're more flavorful, so you can eat less of them and feel satisfied."

Food to Avoid: Light yogurts

"I never buy these!" says Keri Gans, R.D., author of The Small Change Diet. "Many are full of artificial sweeteners, taste fake and often have two thirds less protein than more filling, and more natural, Greek yogurt. The few calories you might save just aren't worth it."

Food to Avoid: Bottled salad dressings

Many are made with chemicals, additives and corn syrup. "If I'm making a salad with fresh vegetables, why would I pour something orange out of a bottle onto it?" says Christine Gerbstadt, M.D., R.D., author of Doctor's Detox Diet. For a tasty, easy, do-it-yourself version, mix a little olive oil, vinegar and your favorite herbs—done!

Food to Avoid: Processed meats

"Lunch meats are often sky-high in sodium and have nitrates, preservatives linked to cancer," says Bannan. Pick organic luncheon meats (they're nitrate-free) with no more than 500 mg of sodium per two-ounce serving.